Complementary ex vivo multimodal optical imaging and in vivo Raman spectroscopy to understand tissue dynamics

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PROJECT SUMMARY Limited approaches exist to examine longitudinal changes in the structural and biochemical properties of tissues under various physiological conditions such as pregnancy. Light and light based technologies offer the potential for non-invasive, real-time, in vivo monitoring of longitudinal shifts in tissue physiology in response to developmental, hormonal, or environmental influences. The objective of the proposed research is to pursue a multi-pronged platform with complementary Raman scattering approaches to study longitudinal changes in tissue physiology in vivo as well as ex vivo and compare the results with conventional assays to validate our approach. In addition, we will combine various forms of in vivo Raman imaging, including (i) dual wavelength, dual region Raman (ii) polarization-sensitive Raman, and (iii) resonance Raman spectroscopy to quantitatively analyze changes in tissue physiology. In response to a lack of detailed understanding of preterm birth and its tissue biochemistry, our group has reported the utility of in vivo RS to detect and extract longitudinal biochemical changes in the mouse as well as human cervix, a tissue that undergoes extensive remodeling over the course of pregnancy. We established the ability of a conventional in vivo RS probe to identify significant spectral changes in collagen, elastin, water, and blood. Moreover, we can correlate these Raman spectra with changes in biomechanical properties of the mouse cervix, including stiffness and distensibility, as the cervical tissue undergoes normal remodeling/maturation in preparation for labor. Building on our prior research, the present proposal will focus multimodal ex vivo and in vivo Raman approaches to gain in-depth, quantitative information during physiologic cervical maturation and in mouse models of premature remodeling. We hypothesize that multimodal Raman approaches will enable detection of key biochemical changes, such as extracellular matrix (ECM) organization, tissue hydration, lipid and protein influx and vascularity that will allow molecular and structural phenotyping of the cervix as a prototype of physiologic tissue remodeling. Results will be correlated with spatial information obtained via ex vivo imaging and biomechanical testing. Our Aims are to: 1) Implement multimodal non-linear imaging to characterize changes in structural proteins in the mouse cervix, 2) Use dual wavelength, dual region Raman Spectroscopy to track changes in tissue hydration and lipid dynamics, and 3) Evaluate spatial and temporal changes in blood and vascularization in the mouse cervix over the course of pregnancy. Ultimately, this project will integrate the results of these aims to provide a more complete picture of the molecular and structural changes that can be used to understand normal as well as compromised pregnancies. The resultant in-depth biomolecular profiles and spatial tissue maps obtained for normal term and preterm pregnancies with the innovative Raman approaches will provide vital information about the mechanism of premature cervical remodeling and for monitoring longitudinal changes in the structural and biochemical properties of other tissues with RS.